Arrange the following pentoxides in order of their increasing acidic strength.
A. \(Bi_2O_5\)
B. \(Sb_2O_5\)
C. \(P_2O_5\)
D. \(As_2O_5\)
E. \(N_2O_5\)
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → A < B < D < C < E
Group 15 elements form oxides of the type E2O5. On going down the group the metallic character increases (N, P non-metals; As, Sb metalloids; Bi a metal), so the acidic character of the oxides decreases down the group:
\( \ce{N2O5} \) > \( \ce{P2O5} \) > \( \ce{As2O5} \) > \( \ce{Sb2O5} \) > \( \ce{Bi2O5} \)
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic is not there in the latest NCERT book (2026-27), and it is also out of the CUET 2026 syllabus.
NCERT (Pre-rationalised edition, 2022-23):
Reactivity towards Oxygen – “All these elements form two types of oxides: E2O3 and E2O5. The oxide in the higher oxidation state of the element is more acidic than that of lower oxidation state. Their acidic character decreases down the group.”